已知sin^2a+sina=1,则cos^4a+cos^2a=?
问题描述:
已知sin^2a+sina=1,则cos^4a+cos^2a=?
答
sina=1-sin^2a=coos^2a
则cos^4a=sin^2a
所以cos^4a+cos^2a
=sin^2a+sina
=1